Method and apparatus for operating a cross-compound turbine generator

Abstract

A cross compound turbine apparatus and method of operating the same wherein the apparatus includes a first turbine generator having a high pressure turbine and a first low pressure turbine connected to a first generator driving shaft, with the second turbine generator having an intermediate pressure turbine connected to a second generator driving shaft. Driving steam is supplied to the high pressure turbine and a primary steam line communicates exhaust steam from the high pressure turbine to drive the intermediate pressure turbine during a steady state operation of the first and second turbine generator sections. A bypass steam line communicates steam from the system supplying driving steam to the high pressure turbine to the intermediate pressure turbine in a bypassing relationship to the high pressure turbine. A control arrangement controls the flow of steam in the primary and bypass steam lines during a starting operating of the turbine generator sections, with the control arrangement being adapted to maintain the relative speeds of the first and second generator driving shafts in a predetermined synchronsis ratio. A controllable vent arrangement is provided for venting a portion of the steam flow in the primary steam line during starting operations. By virtue of these features, a speed synchronization of multiturbine sections can be obtained in an efficient and inexpensive manner without causing excessive heat rise in the turbine blades.